People don't value your same words after a certain time.There are times when people need us so much that we feel that our or our word's value is the highest, but that value is really at that time only. Suppose you are a good motivational speaker, then a person would like to hear you more when he/she needs motivation or when he. she is upset. Apart from this, when the time is going well in their life, they are climbing up the ladder of progress, then perhaps your same words will look like a boring speech to them.
I am not saying that our words are not worth it, but perhaps the value and importance of our words also change as per the time and demand and we should understand that when our words are going in vain and we ourselves needs to be silenced.